Nancy Wood had identified areas of radioactive mineral accumulation as sites of interest for biological sampling. This is because the natural radioactivity provides a an environmental stress to the microbial community that partly mimics the shallow subsurface environment of Mars which are exposed to high levels of background radiation because of solar particles, galactic gamma rays, and cosmic rays. Uranium mineralisation is unlikely on Mars because the crust is throught to be insufficiently evolved. Because the Morrison Formation, which crops out throughout much of the MDRS field area, is a major host for uranium mineralisation in the region, There are several localities that can be sampled.

On Monday March 3rd a team of three members from Expedition One visited a uranium prospect south west of Factory Butte. No production from the site is recorded in . Apart from a discused track, all that remains on this site is an adit and a pile of spoil and low grade ore. The uranium mineralisation occurs in coarse carbonaceous sandstone to conglomerate. The geiger counter recorded radioactivity of up to 0.3 millirems per hour from some samples. The abundance of organic matter suggests that primary mineralisation was uraninite (UO2),also known as pitchblende. Some dark apple green radioactive minerals were also found, these were tentatively identified as the seondary uranium mineral torbanite (Cu(UO2)2(PO4)2.8-12H2O) or autunite (Ca(UO2)2(PO4)2.10-12H2O).

On the night of Thursday March 6th we were able to darken the laboratory space on the lower deck and examine Samples of sandstone with a green coating, and fossil wood bearing carbonaceous sandstone and conglomerate under ultraviolet light. The UV lamp revealed extensive areas of green, yellow, orange fluorescence, together with minor flecks of blue. The suspected torbanite or autanite fluoresced green, indicating that it was torbanite. Yellow fluorescence indicated tyuyamunite (Ca(UO2)2(vo4)2.5-81/2H2O),the identity of the blue and orange fluorescent minerals is not known, although the orange fluorescence was found only on the fossil wood.

For safety reasons the samples will be returned to the prospect before the end of Expedition One.